Fibrous structures comprising a polymer structure

ABSTRACT

Polymer structures and methods for making such polymer structures are provided. More particularly, polymer structures comprising a hydroxyl polymer structure, such as a fiber comprising a hydroxyl polymer are provided. Even more particularly, fibrous structures comprising a hydroxyl polymer structure, such as a fiber comprising a hydroxyl polymer, wherein the fibrous structure exhibits a CETM Factor of less than 20 and/or a CETM*L 2  Factor of less than 950 are provided.

FIELD OF THE INVENTION

The present invention relates to polymer structures and methods formaking such polymer structures. More particularly, the present inventionrelates to polymer structures comprising a hydroxyl polymer structure,such as a fiber comprising a hydroxyl polymer. Even more particularly,the present invention relates to fibrous structures comprising ahydroxyl polymer structure, such as a fiber comprising a hydroxylpolymer, wherein the fibrous structure exhibits a CETM Factor of lessthan 20 and/or a CETM*L² Factor of less than 950.

BACKGROUND OF THE INVENTION

Fibrous structures that exhibit a CETM Factor of 21 or greater and/or aCETM*L² Factor of greater than 1000 are known in the art. For example,fibrous structures that comprise a fiber comprising a hydroxyl polymerthat exhibit a CETM Factor of 21 or greater and/or that exhibit aCETM*L² Factor of greater than 1000 are known in the art.

It is known that sanitary tissue products comprising a fibrous structurethat exhibits a CETM Factor of 21 or greater and/or that exhibits aCETM*L² Factor of greater than 1000 do not exhibit consumer acceptableproperties such as linting and/or pilling, especially wet linting and/orwet pilling, dry linting and/or dry pilling, and/or softness.

Accordingly, there is a need for a fibrous structure that exhibits aCETM Factor of less than 20 and/or a CETM*L² Factor of less than 950;methods for making such fibrous structures and sanitary tissue productscomprising such fibrous structures.

SUMMARY OF THE INVENTION

The present invention fulfills the needs described above by providing afibrous structure that exhibits a CETM Factor of less than 20 and/or aCETM*L² Factor of less than 950.

In one example of the present invention, a fibrous structure comprisinga hydroxyl polymer structure, such as a hydroxyl polymer fiber and/orfilm and/or foam, wherein the fibrous structure exhibits a CETM Factorof less than 20 is provided.

In another example of the present invention, a fibrous structurecomprising a hydroxyl polymer structure, such as a hydroxyl polymerfiber and/or film and/or foam, wherein the fibrous structure exhibits aCETM*L² Factor of less than 950 is provided.

In even another example of the present invention, a process for making afibrous structure comprising a hydroxyl polymer structure, wherein thefibrous structure exhibits a CETM Factor of less than 20 and/or aCETM*L² Factor of less than 950, the process comprising the steps of:

a. producing a hydroxyl polymer structure in the form of a fiber;

b. forming a fibrous structure comprising the hydroxyl polymer fiber;

c. subjecting the fibrous structure to a thermal bonding operation, isprovided.

In even still yet another example of the present invention, a single- ormulti-ply sanitary tissue product comprising a fibrous structure of thepresent invention is provided.

Accordingly, the present invention provides fibrous structures thatexhibits a CETM Factor of less than 20 and/or a CETM*L² Factor of lessthan 950; methods for making such a fibrous structure and sanitarytissue products comprising such a fibrous structure; and processes formaking a fibrous structure of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a schematic representation of a side view of a barrel of atwin screw extruder suitable for use in the present invention.

FIG. 1B is a schematic side view of a screw and mixing elementconfiguration suitable for use in the barrel of FIG. 1A.

FIG. 2 is a schematic representation of a process for making a fibrousstructure in accordance with the present invention;

FIG. 3 is a schematic representation of a fibrous structure inaccordance with the present invention;

FIG. 4 is a schematic cross-sectional representation of the fibrousstructure of FIG. 3 taken along line 4-4;

FIG. 5A is a scanning electron microscope photograph of an unfusedregion of a fibrous structure in accordance with the present invention;

FIG. 5B is a scanning electron microscope photograph of a fused regionof a fibrous structure in accordance with the present invention;

FIG. 6 is a schematic representation of a process for making a fibrousstructure in accordance with the present invention;

FIG. 7 is a flowchart representing in schematic cross-sectionalrepresentation of examples of fibrous structures (7A-7D) formedaccording to the processes of the present invention;

DETAILED DESCRIPTION OF THE INVENTION Definitions

“Polymer structure” as used herein means any single physical structureproduced by a polymer or polymer composition comprising at least onepolymer. The polymer structures are produced from a polymer compositionthat is polymer processed into the physical structure. The polymerstructures may be dry spun and/or solvent spun. “Dry spinning”, “dryspun” and/or “solvent spinning”, “solvent spun” as used herein unlikewet spinning means that polymer structures are not spun into acoagulating bath.

The polymer structures of the present invention are non-naturallyoccurring polymer structures. In other words, the polymer structures ofthe present invention do not include naturally occurring cellulosefibers. Nonlimiting examples of polymer structures in accordance withthe present invention include fibers, films and foams. A plurality ofpolymer structure fibers may combine to form a fibrous structure (web).

The polymer structures of the present invention may be combined withother non-polymer structure physical structures, such as naturallyoccurring cellulose fibers, to form a fibrous structure. In one example,the polymer structure of the present invention as a whole (fiber,fibrous structure, film and/or foam) has no melting point. It is alsodesirable that the polymer structure (fiber, fibrous structure, filmand/or foam) of the present invention be substantially homogeneous orcompletely homogeneous.

In one example, the polymer structures of the present invention do notcontain water-insoluble thermoplastic polymers.

In another example, the polymer structures of the present invention donot consist of inherently thermoplastic polymers.

In yet another example, the polymer structures of the present inventiondo not contain non-hydroxyl-containing thermoplastic polymers.

The polymer structures of the present invention, especially fibers ofthe present invention, may be produced by crosslinking polymers, such ashydroxyl polymers, together. Nonlimiting examples of a suitablecrosslinking system for achieving crosslinking comprises a crosslinkingagent and optionally a crosslinking facilitator, wherein the hydroxylpolymer is crosslinked by the crosslinking agent.

A “fibrous structure” as used herein means a single web structure thatcomprises at least one fiber. For example, a fibrous structure of thepresent invention may comprise one or more fibers, wherein at least oneof the fibers comprises a hydroxyl polymer structure in fiber form. Inanother example, a fibrous structure of the present invention maycomprise a plurality of fibers, wherein at least one (sometimes amajority, even all) of the fibers comprises a hydroxyl polymer structurein fiber form. The fibrous structures of the present invention may belayered such that one layer of the fibrous structure may comprise adifferent composition of fibers and/or materials from another layer ofthe same fibrous structure.

Polymer structures of the present invention do not include coatingsand/or other surface treatments comprising a hydroxyl polymer (such asstarch sizing compositions) that are applied to a pre-existing form,such as a coating on a fiber, film or foam. However, in one embodimentof the present invention, a polymer structure in accordance with thepresent invention may be coated and/or surface treated with thecrosslinking system of the present invention.

The polymer structures in fiber, fibrous structure, film and/or foamform may be incorporated into sanitary tissue products and/or otherpaper-like products, such as writing papers, cores, such as tissueproduct cores, packaging films, and packaging peanuts.

One or more polymer structures of the present invention may beincorporated into a multi-polymer structure product.

“Hydroxyl polymer structure” as used herein means a polymer structure ofthe present invention wherein the polymer structure comprises a hydroxylpolymer.

“Hydroxyl polymer” as used herein includes any hydroxyl-containingpolymer that can be incorporated into a polymer structure of the presentinvention, such as into a polymer structure in the form of a fiber.

In one embodiment, the hydroxyl polymer of the present inventionincludes greater than 10% and/or greater than 20% and/or greater than25% by weight hydroxyl moieties.

Nonlimiting examples of hydroxyl polymers in accordance with the presentinvention include polyols, such as polyvinyl alcohol, polyvinyl alcoholderivatives, polyvinyl alcohol copolymers, starch, starch derivatives,chitosan, chitosan derivatives, cellulose derivatives such as celluloseether and ester derivatives, gums, arabinans, galactans, proteins andvarious other polysaccharides and mixtures thereof.

Classes of hydroxyl polymers are defined by the hydroxyl polymerbackbone. For example polyvinyl alcohol and polyvinyl alcoholderivatives and polyvinyl alcohol copolymers are in the class ofpolyvinyl alcohol hydroxyl polymers whereas starch and starchderivatives are in the class of starch hydroxyl polymers.

The hydroxyl polymer may have a weight average molecular weight of fromabout 10,000 to about 40,000,000 g/mol. Higher and lower molecularweight hydroxyl polymers may be used in combination with hydroxylpolymers having the preferred weight average molecular weight.

Well known modifications of hydroxyl polymer, such as natural starches,include chemical modifications and/or enzymatic modifications. Forexample, the natural starch can be acid-thinned, hydroxy-ethylated,hydroxy-propylated, and/or oxidized. In addition, the hydroxyl polymermay comprise dent corn starch hydroxyl polymer.

Polyvinyl alcohols herein can be grafted with other monomers to modifyits properties. A wide range of monomers has been successfully graftedto polyvinyl alcohol. Nonlimiting examples of such monomers includevinyl acetate, styrene, acrylamide, acrylic acid, 2-hydroxyethylmethacrylate, acrylonitrile, 1,3-butadiene, methyl methacrylate,methacrylic acid, vinylidene chloride, vinyl chloride, vinyl amine and avariety of acrylate esters.

“Polysaccharides” as used herein means natural polysaccharides andpolysaccharide derivatives or modified polysaccharides. Suitablepolysaccharides include, but are not limited to, starches, starchderivatives, chitosan, chitosan derivatives, cellulose derivatives,gums, arabinans, galactans and mixtures thereof. In one example, thehydroxyl polymer comprises and/or consists essentially of and/orconsists of one or more polysaccharides.

“Fiber” as used herein means a slender, thin, and highly flexible objecthaving a major axis which is very long, compared to the fiber's twomutually-orthogonal axes that are perpendicular to the major axis.Preferably, an aspect ratio of the major's axis length to an equivalentdiameter of the fiber's cross-section perpendicular to the major axis isgreater than 100/1, more specifically greater than 500/1, and still morespecifically greater than 1000/1, and even more specifically, greaterthan 5000/1.

The fibers of the present invention may be continuous or substantiallycontinuous. In one example, a fiber is continuous or substantiallycontinuous if it extends 100% of the MD length of the fibrous structureand/or fibrous structure and/or sanitary tissue product made therefrom.In one embodiment, a fiber is substantially continuous if it extendsgreater than about 5% and/or greater than about 10% and/or greater thanabout 20% and/or greater than about 30% and/or greater than about 50%and/or greater than about 70% of the MD length of the fibrous structureand/or sanitary tissue product made therefrom. In another example, afiber is continuous or substantially continuous if it exhibits a lengthof at least about 2.54 cm (1 inch) and/or at least about 3.81 cm (1.5inches) and/or at least about 5.08 cm (2 inches) and/or at least about6.35 cm (2.5 inches) and/or at least about 7.62 cm (3 inches).

The fiber can have a fiber diameter as determined by the Fiber DiameterTest Method described herein of less than about 50 microns and/or lessthan about 20 microns and/or less than about 10 microns and/or less thanabout 8 microns and/or less than about 6 microns and/or less than about5.5 microns.

The fibers may include melt spun fibers, dry spun fibers and/or spunbondfibers, staple fibers, hollow fibers, shaped fibers, such as multi-lobalfibers and multicomponent fibers, especially bicomponent fibers. Themulticomponent fibers, especially bicomponent fibers, may be in aside-by-side, sheath-core, segmented pie, ribbon, islands-in-the-seaconfiguration, or any combination thereof. The sheath may be continuousor non-continuous around the core. The ratio of the weight of the sheathto the core can be from about 5:95 to about 95:5. The fibers of thepresent invention may have different geometries that include round,elliptical, star shaped, rectangular, and other various eccentricities.

“Sanitary tissue product” as used includes but is not limited to awiping implement for post-urinary and post-bowel movement cleaning(toilet tissue), for otorhinolaryngological discharges (facial tissue),and multi-functional absorbent, cleaning uses (absorbent towels), wipes,feminine care products and diapers.

A sanitary tissue product of the present invention comprises at leastone polymer structure and/or fibrous structure in accordance with thepresent invention. In one example, a polymer structure and/or a fibrousstructure and/or sanitary tissue product according to the presentinvention exhibits an initial total wet tensile, as measured by theInitial Total Wet Tensile Test Method described herein, of at leastabout 8 g/2.54 cm (8 g/in) and/or at least about 10 g/2.54 cm (10 g/in)and/or at least about 15 g/2.54 cm (15 g/in) and/or at least about 20g/2.54 cm (20 g/in) and/or at least about 40 g/2.54 cm (40 g/in).

In another example, a polymer structure and/or a fibrous structureand/or a sanitary tissue product of the present invention exhibits aninitial total wet tensile, as measured by the Initial Total Wet TensileTest Method described herein, of less than about 500 g/2.54 cm (500g/in) and/or less than about 400 g/2.54 cm (400 g/in) and/or less thanabout 300 g/2.54 cm (300 g/in) and/or less than about 200 g/2.54 cm (200g/in) and/or less than about 150 g/2.54 cm (150 g/in) and/or less thanabout 120 g/2.54 cm (120 g/in) and/or less than about 100 g/2.54 cm (100g/in).

In yet another example, polymer structure and/or a fibrous structureand/or a sanitary tissue product of the present invention may exhibit aninitial total wet tensile, as measured by the Initial Total Wet TensileTest Method described herein, of from about 8 g/2.54 cm (8 g/in) toabout 500 g/2.54 cm (500 g/in) and/or from about 40 g/2.54 cm (40 g/in)to about 500 g/2.54 cm (500 g/in) and/or from about 60 g/2.54 cm (60g/in) to about 500 g/2.54 cm (500 g/in) and/or from about 65 g/2.54 cm(65 g/in) to about 450 g/2.54 cm (450 g/in) and/or from about 70 g/2.54cm (70 g/in) to about 400 g/2.54 cm (400 g/in) and/or from about 75g/2.54 cm (75 g/in) to about 400 g/2.54 cm (400 g/in) and/or from about80 g/2.54 cm (80 g/in) to about 300 g/2.54 cm (300 g/in) and/or fromabout 80 g/2.54 cm (80 g/in) to about 200 g/2.54 cm (200 g/in) and/orfrom about 80 g/2.54 cm (80 g/in) to about 150 g/2.54 cm (150 g/in)and/or from about 80 g/2.54 cm (80 g/in) to about 120 g/2.54 cm (120g/in) and/or from about 80 g/2.54 cm (80 g/in) to about 100 g/2.54 cm(100 g/in).

In one example, polymer structure and/or a fibrous structure and/or asanitary tissue product according to the present invention exhibits aminimum total dry tensile of at least about 70 g/2.54 cm (70 g/in)and/or at least about 100 g/2.54 cm (100 g/in) and/or at least about 300g/2.54 cm (300 g/in) and/or at least about 500 g/2.54 cm (500 g/in)and/or at least about 700 g/2.54 cm (700 g/in) and/or at least about 800g/2.54 cm (800 g/in) and/or at least about 900 g/2.54 cm (900 g/in)and/or at least about 1000 g/2.54 cm (1000 g/in).

In another example, polymer structure and/or a fibrous structure and/ora sanitary tissue product according to the present invention exhibits amaximum total dry tensile of less than about 5000 g/2.54 cm (5000 g/in)and/or less than about 4000 g/2.54 cm (4000 g/in) and/or less than about2000 g/2.54 cm (2000 g/in) and/or less than about 1700 g/2.54 cm (1700g/in) and/or less than about 1500 g/2.54 cm (1500 g/in).

In even another example, polymer structure and/or a fibrous structureand/or a sanitary tissue product according to the present inventionexhibits a wet lint score of less than about 25 and/or less than 20and/or less than 15 and/or less than 10 as measured according to theLint/Pilling Test Method described herein.

In yet another example, a sanitary tissue product according to thepresent invention exhibits a total dry tensile within a range of aminimum and maximum total dry tensile value as described above.

In still yet another example, polymer structure and/or a fibrousstructure and/or a sanitary tissue product according to the presentinvention exhibits a Dry Lint Score of less than about 10 and/or lessthan about 8 and/or less than about 7 and/or less than about 6 and/orless than about 5.5 as measured according to the Lint/Pilling TestMethod described herein.

“Ply” or “Plies” as used herein means a single fibrous structureoptionally to be disposed in a substantially contiguous, face-to-facerelationship with other plies, forming a multi-ply sanitary tissueproduct. It is also contemplated that a single fibrous structure caneffectively form two “plies” or multiple “plies”, for example, by beingfolded on itself. Ply or plies can also exist as films or other polymerstructures.

One or more layers may be present in a single ply. For example, two ormore layers of different compositions may form a single ply. In otherwords, the two or more layers are substantially or completely incapableof being physically separated from each other without substantiallydamaging the ply.

“Weight average molecular weight” as used herein means the weightaverage molecular weight as determined using gel permeationchromatography according to the protocol found in Colloids and SurfacesA. Physico Chemical & Engineering Aspects, Vol. 162, 2000, pg. 107-121.

“Lint” and/or “Pills” as used herein means discrete pieces of a polymerstructure and/or fibrous structure and/or sanitary tissue product thatbecome separated from the original polymer structure and/or fibrousstructure and/or sanitary tissue product, respectively, typically duringuse.

For example, known bath tissues and paper towels are comprised offibrous structures consisting essentially of short cellulose fibers.During a wiping process—both wet and dry, these short cellulosic fiberscan detach from the fibrous structure and become evident as lint orpills. The present invention employs essentially continuous orsubstantially continuous fibers vs. traditional discrete, shortcellulosic fibers. Generally speaking, fibrous structures of the presentinvention resist linting vs. their cellulosic fiber-based cousins due tothe continuous nature of the fibers of the present invention.Furthermore, polymer structures and/or fibrous structures and/orsanitary tissue products of the present invention will resist pillingvs. their cellulosic fiber-based cousins provided the bonding and fiberstrength and stretch are sufficient enough to prevent free fiberbreakage and entanglement with adjacent fibers during the wipingprocess.

“Intensive Properties” and/or “Values of Common Intensive Properties” asused herein means a property of the polymer structure, fibrous structureand/or sanitary tissue product (collectively referred to as“substrate”—which means a single, unitary structure, not multipleunitary structures stacked one on top of the other) of the presentinvention that is independent of mass. Nonlimiting examples of commonintensive properties include density, substrate basis weight, substratecaliper, substrate thickness, substrate elevation, substrate opacity,substrate crepe frequency, and any combination thereof. The polymerstructures and/or fibrous structures and/or sanitary tissue products ofthe present invention may comprise two or more regions that exhibitdifferent values of common intensive properties relative to each other.In other words, a fibrous structure of the present invention maycomprise one region having a first opacity value and a second regionhaving a second opacity value different from the first opacity value.Such regions may be continuous, substantially continuous and/ordiscontinuous. Various common intensive properties can be measured bythe methods described in U.S. Pat. No. 5,843,279 to Phan et al. and U.S.Pat. No. 5,328,565 to Rasch et al. all owned by The Procter & GambleCompany.

“Thermal bonding operation” as used herein means that a material, suchas a polymer structure, especially a fibrous structure comprising ahydroxyl polymer structure according to the present invention, isimparted properties that result in one or more of the polymers of thepolymer structure to exhibit a temperature above its Tg. Once thepolymer is imparted a temperature above its Tg, then the polymer canflow thus facilitating fusing of fibers and/or polymer structures wherea pressure is applied.

The conditions at which the thermal bonding operation occurs can varydepending upon the values of each of the conditions. For example, thefollowing conditions are the primary conditions that impact the thermalbonding operation of a fibrous structure comprising one or more fibersformed from one or more hydroxyl polymers of the present invention: 1)level of a Tg modifying agent, such as a polyvinyl alcohol hydroxylpolymer; 2) temperature of the fibrous structure during the thermalbonding operation; 3) pressure applied to the fibrous structure duringthe thermal bonding operation; 4) humidity at which the fibrousstructure is subjected to during the thermal bonding operation; and 5)time (residence time) that the fibrous structure is at the temperature,under the pressure and/or at the humidity described above. For example,if temperature of the fibrous structure is increased, pressure may bedecreased to obtain thermal bonding of a fibrous structure comprisingpolymer structures of the present invention, in one case such that thefibrous structure meets the CETM factor and/or CETM*L² factor of thepresent invention. The conditions at which thermal bonding of a fibrousstructure according to the present invention may occur, in one case suchthat the fibrous structure meets the CETM factor and/or CETM*L² factor,can be empirically derived by experimentation.

For example, at a given level of Tg modifying agent (such as polyvinylalcohol hydroxyl polymer), the temperature of the fibrous structure mayneed to be increased or decreased and/or the pressure may need to beincreased or decreased and/or the humidity may need to be increased ordecreased and/or the time at which the fibrous structure is at thetemperature, under the pressure and at the humidity may need to beincreased or decreased.

In another example, at a given temperature of the fibrous structure, thelevel of Tg modifying agent (such as polyvinyl alcohol hydroxyl polymer)may need to be increased or decreased and/or the pressure may need to beincreased or decreased and/or the humidity may need to be increased ordecreased and/or the time at which the fibrous structure is at thetemperature, under the pressure and at the humidity may need to beincreased or decreased.

Similar scenarios would exist at a given pressure, at a given humidityand at a given time at which the fibrous structure is at thetemperature, under the pressure and at the humidity may need to beincreased or decreased.

In one example, the Tg of a fiber and/or one or more polymers (starchand polyvinyl alcohol hydroxyl polymer, for example) within the fiberwhich is present within a fibrous structure according to the presentinvention, is decreased or increased compared to the starting Tg basedupon the level of polyvinyl alcohol hydroxyl polymer included in thefiber. For example, if 5% wt. of polyvinyl alcohol hydroxyl polymer ispresent in the fiber then the Tg of the fiber and/or one or morepolymers within the fiber is increased. In contrast, if 20% wt. ofpolyvinyl alcohol hydroxyl polymer is present in the fiber then the Tgof the fiber and/or one or more polymers within the fiber is decreased.Therefore, the temperature at which the fibrous structure needs to be atin order for its fibers to be at a temperature above its fibers' Tgand/or one or more polymers' Tg depends upon the level of polyvinylalcohol hydroxyl polymer present in the fibers.

For example, a polymer structure comprising a polyvinyl alcohol hydroxylpolymer and a starch hydroxyl polymer can be at any suitable temperaturedepending upon the conditions for the thermal bonding operation asdiscussed above. Nonlimiting examples suitable temperatures of thepolymer structure and/or polymers within the polymer structure for thethermal bonding operation include a temperature of from about 70° C.(158° F.) to about 400° C. (752° F.) and/or from about 80° C. (176° F.)to about 260° C. (500° F.) so long as the polymer structure and/or oneor more polymers making up the polymer structure are at a temperatureabove its Tg during the thermal bonding operation, thus subjecting thepolymer structure and/or one or more polymers making up the polymerstructure to a temperature above its Tg. Depending on the materialswithin the polymer structure, some of the materials may burn and/or charat temperatures above a certain maximum. In another example, dependingupon the materials present in the polymer structure, especially if thepolymer structure has not been cured at the time of the thermal bondingoperation, a temperature of the polymer structure of less than 170° C.(338° F.), and/or less than about 140° C. (285° F.) and/or less thanabout 104° C. (220° F.) and/or less than about 90° C. (194° F.) and/oreven about 82° C. (180° F.), may be utilized to obtain thermal bonding.Accordingly, in one example the polymer structure, especially an uncuredpolymer structure, may exhibit a temperature of greater than about 70°C. (158° F.) and/or greater than about 80° C. (176° F.) and/or greaterthan about 90° C. (194° F.) and/or greater than about 104° C. (220° F.)and/or from about 70° C. (158° F.) to about 400° C. (752° F.) and/orfrom about 80° C. (176° F.) to about 260° C. (500° F.) and/or from about104° C. (220° F.) to about 200° C. (392° F.) and/or from about fromabout 120° C. (248° F.) to about 200° C. (392° F.) and/or from aboutfrom about 140° C. (285° F.) to about 200° C. (392° F.) and/or fromabout from about 170° C. (338° F.) to about 200° C. (392° F.). Thermalbonding of uncured polymer structures may reduce the piling of thepolymer structures and/or fibrous structures containing such polymerstructures and/or sanitary tissue products comprising such polymerstructures. In another example, if humidity, such as relative humidityin the range of 70 to 85% RH is present in combination with a lowertemperature of the polymer structure, such as 110° C. (230° F.) to about130° C. (266° F.), the polyvinyl alcohol hydroxyl polymer within apolymer structure may flow since the presence of the relative highhumidity decreases the Tg of the polyvinyl alcohol hydroxyl polymer.

“Fused” as in “fused region” as used herein means that two or morephysical structures, such as polymer structures, even more particularlyhydroxyl polymer structures, such as hydroxyl polymer fibers, arephysically and/or chemically combined into a unitary structure. In oneexample, a fused region may comprise two or more fibers that sharecommon material between the fibers such that the two or more fibers forma unitary structure. In another example, a fused region may comprise twoor more fibers that have an adhesive agent, such as an elastomeric agent(i.e., a latex), that binds the two or more fibers into a unitarystructure.

“Unfused” as in “unfused region” as used herein means that two or morephysical structures, such as polymer structures, even more particularlyhydroxyl polymer structures, such as hydroxyl polymer fibers, arephysically and chemically discrete from each other.

In one example, a fused region of a fibrous structure of the presentinvention exhibits a lower opacity value than an unfused region withinthe same fibrous structure.

In another example, a fused region of a fibrous structure of the presentinvention is present in the form of a non-random repeating patternwithin the fibrous structure.

“CETM Factor” as used herein is the quotient of Initial Total WetTensile in grams/inch units divided by Dry Burst Energy in(grams_(force)×cm)/cm². The Initial Total Wet Tensile is measuredaccording to the Initial Total Wet Tensile Test Method described herein.The Dry Burst Energy is measured according to the Dry Burst Energy TestMethod described herein.

In one example, a fibrous structure in accordance with the presentinvention exhibits a CETM Factor of less than 20 and/or less than 19.5and/or less than 19 and/or less than 18 and/or less than 17 and/or lessthan 16.

“CETM*L² Factor” as used herein is the product of CETM Factor×(Dry LintScore). The Dry Lint Score is measured according to the Dry Lint ScoreTest Method described herein. It has been surprisingly found that thedry lint score of the fibrous structures of the present invention isdisproportionately important in determining whether the fibrousstructures of the present invention and/or sanitary tissue productscomprising such fibrous structures are acceptable to consumers.

In one example, a fibrous structure in accordance with the presentinvention exhibits a CETM*L² Factor of less than 950 and/or less than900 and/or less than 850 and/or less than 800 and/or less than 700and/or less than 500 and/or less than 300 and/or 150 and/or less than100 and/or less than 60.

“Capillary Number” as used herein is a number representing the ratio ofthe viscous fluid forces to surface tension forces. Near the exit of acapillary die, if the viscous forces are not significantly larger thanthe surface tension forces, the fluid filament will break into droplets,which is commonly termed “atomization.” The Capillary Number iscalculated according to the following equation:Ca=(η_(s) ·Q)/(π·r ²·σ)where η_(s) is the shear viscosity in Pascal·seconds measured at a shearrate of 3000 s⁻¹; Q is the volumetric fluid flow rate through capillarydie in m³/s; r is the radius of the capillary die in meters (fornon-circular orifices, the equivalent diameter/radius can be used); andσ is the surface tension of the fluid in Newtons per meter.

“Caliper” as used herein means the macroscopic thickness of a sample.Caliper of a sample of fibrous structure according to the presentinvention is determined by cutting a sample of the fibrous structuresuch that it is larger in size than a load foot loading surface wherethe load foot loading surface has a circular surface area of about 3.14in². The sample is confined between a horizontal flat surface and theload foot loading surface. The load foot loading surface applies aconfining pressure to the sample of 15.5 g/cm² (about 0.21 psi). Thecaliper is the resulting gap between the flat surface and the load footloading surface. Such measurements can be obtained on a VIR ElectronicThickness Tester Model II available from Thwing-Albert InstrumentCompany, Philadelphia, Pa. The caliper measurement is repeated andrecorded at least five (5) times so that an average caliper can becalculated.

All percentages and ratios are calculated by weight unless otherwiseindicated. All percentages and ratios are calculated based on the totalcomposition unless otherwise indicated.

Unless otherwise noted, all component or composition levels are inreference to the active level of that component or composition, and areexclusive of impurities, for example, residual solvents or by-products,which may be present in commercially available sources.

Hydroxyl Polymer Structure

The hydroxyl polymer structure of the present invention may comprise afirst polymer and a second polymer, wherein one of the two polymers isinherently thermoplastic (a polymer that melts and/or flows without theneed of a plasticizer when the polymer is imparted a temperature aboveits Tg). The other polymer may require a plasticizer, such as water,sorbitol, glycerine, polyols, such as polyethylene glycols, ethyleneglycol, polyethylene glycol, urea, sucrose, and esters, and combinationsthereof to permit it to melt and/or flow when the polymer is imparted atemperature above its Tg (i.e., a thermoplasticizable polymer). In oneexample, the first polymer and the second polymer are hydroxyl polymers.In another example, the first polymer and the second polymer aredifferent classes of hydroxyl polymers, such as starch hydroxyl polymerand polyvinyl alcohol hydroxyl polymer. The polymers of the hydroxylpolymer structure may be crosslinkable via a crosslinking system tothemselves and/or to the each other.

The hydroxyl polymer structure of the present invention can be producedby polymer processing, for example meltblowing, spunbonding, and/orrotary spinning, a polymer composition.

Polymer Composition

The polymer composition of the present invention may have a shearviscosity, as measured according to the Shear Viscosity of a PolymerComposition Measurement Test Method described herein, of from about 0.5Pascal·Seconds to about 25 Pascal·Seconds and/or from about 1Pascal·Seconds to about 25 Pascal·Seconds and/or from about 1.5Pascal·Seconds to about 25 Pascal·Seconds and/or from about 2Pascal·Seconds to about 20 Pascal·Seconds and/or from about 3Pascal·Seconds to about 10 Pascal·Seconds, as measured at a shear rateof 3,000 sec⁻¹ and at the processing temperature (50° C. to 100° C.).Additionally, the normalized shear viscosity of the polymer compositionof the present invention, in one example, does not increase more than1.3 times the initial shear viscosity value after 70 minutes and/or 2times the initial shear viscosity value after 130 minutes when measuredat a shear rate of 3,000 sec⁻¹ according to the Shear Viscosity ChangeTest Method described herein.

The polymer composition may have a temperature of from about 50° C. toabout 100° C. and/or from about 65° C. to about 95° C. and/or from about70° C. to about 90° C. when making fibers from the polymer composition.The polymer composition temperature is generally higher when making filmand/or foam polymer structures, as described below.

The pH of the polymer composition may be from about 2.5 to about 9and/or from about 3 to about 8.5 and/or from about 3.2 to about 8 and/orfrom about 3.2 to about 7.5.

In one embodiment, a polymer composition of the present invention maycomprise from about 30% and/or 40% and/or 45% and/or 50% to about 75%and/or 80% and/or 85% and/or 90% and/or 95% and/or 99.5% by weight ofthe polymer composition of a hydroxyl polymer. In one example, thepolymer composition may comprise at least 5% and/or at least 10% and/orat least 13% and/or at least 17% and/or at least 20% and/or at least 30%by weight of the polymer composition of an inherently thermoplasticpolymer, such as polyvinyl alcohol hydroxyl polymer.

The hydroxyl polymer may have a weight average molecular weight greaterthan about 100,000 g/mol prior to crosslinking.

The polymer composition may exhibit a Capillary Number of at least 1and/or at least 3 and/or at least 5 such that the polymer compositioncan be effectively polymer processed into a polymer structure, such as afiber. In one example, the polymer composition exhibits a CapillaryNumber of from at least 1 to about 50 and/or at least 3 to about 50and/or at least 5 to about 30. Further, the polymer composition mayexhibit a pH of from at least about 4 to about 12 and/or from at leastabout 4.5 to about 11.5 and/or from at least about 4.5 to about 11.

A crosslinking system may be present in the polymer composition and/ormay be added to the polymer composition before polymer processing of thepolymer composition. Further, a crosslinking system may be added to thepolymer structure after polymer processing the polymer composition.

The crosslinking system of the present invention may further comprise,in addition to the crosslinking agent, a crosslinking facilitator.

“Crosslinking agent” as used herein means any material that is capableof crosslinking a hydroxyl polymer within a polymer compositionaccording to the present invention.

Nonlimiting examples of suitable crosslinking agents includepolycarboxylic acids, imidazolidinones and other compounds resultingfrom alkyl substituted or unsubstituted cyclic adducts of glyoxal withureas, thioureas, guanidines, methylene diamides, and methylenedicarbamates and derivatives thereof; and mixtures thereof.

“Crosslinking facilitator” as used herein means any material that iscapable of activating a crosslinking agent thereby transforming thecrosslinking agent from its unactivated state to its activated state.

Upon crosslinking the hydroxyl polymer, the crosslinking agent becomesan integral part of the polymer structure as a result of crosslinkingthe hydroxyl polymer as shown in the following schematic representation:

Hydroxyl Polymer·Crosslinking Agent·Hydroxyl Polymer

The crosslinking facilitator may include derivatives of the materialthat may exist after the transformation/activation of the crosslinkingagent. For example, a crosslinking facilitator salt being chemicallychanged to its acid form and vice versa.

Nonlimiting examples of suitable crosslinking facilitators include acidshaving a pKa of between 2 and 6 or salts thereof. The crosslinkingfacilitators may be Bronsted Acids and/or salts thereof, such asammonium salts thereof.

In addition, metal salts, such as magnesium and zinc salts, can be usedalone or in combination with Bronsted Acids and/or salts thereof, ascrosslinking facilitators.

Nonlimiting examples of suitable crosslinking facilitators includeacetic acid, benzoic acid, citric acid, formic acid, glycolic acid,lactic acid, maleic acid, phthalic acid, phosphoric acid, succinic acidand mixtures thereof and/or their salts, such as their ammonium salts,such as ammonium glycolate, ammonium citrate, ammonium chloride andammonium sulfate.

Additional nonlimiting examples of suitable crosslinking facilitatorsinclude glyoxal bisulfite salts, primary amine salts, such ashydroxyethyl ammonium salts, hydroxypropyl ammonium salt, secondaryamine salts, ammonium toluene sulfonate, ammonium benzene sulfonate andammonium xylene sulfonate.

In another embodiment, the crosslinking system of the present inventionmay be applied to a pre-existing form as a coating and/or surfacetreatment.

The polymer composition may comprise a) from about 30% and/or 40% and/or45% and/or 50% to about 75% and/or 80% and/or 85% and/or 90% and/or99.5% by weight of the polymer composition of one or more hydroxylpolymers; b) a crosslinking system comprising from about 0.1% to about10% by weight of the polymer composition of a crosslinking agent; and c)from about 0% and/or 10% and/or 15% and/or 20% to about 50% and/or 55%and/or 60% and/or 70% by weight of the polymer composition of anexternal plasticizer e.g., water.

The polymer composition may comprise two or more different classes ofhydroxyl polymers at weight ratios of from about 20:1 and/or from about15:1 and/or from about 10:1 and/or from about 5:1 and/or from about 2:1and/or from about 1:1 to about 1:20 and/or to about 1:15 and/or to about1:10 and/or to about 1:5 and/or to about 1:2 and/or to about 1:1.

In one example, the polymer composition comprises from about 0.01% toabout 20% and/or from about 0.1% to about 15% and/or from about 1% toabout 12% and/or from about 2% to about 10% by weight of a first classof hydroxyl polymer, such as a polyvinyl alcohol hydroxyl polymer andfrom about 20% to about 99.99% and/or from about 25% to about 95% and/orfrom about 30% to about 90% and/or from about 40% to about 70% by weightof a second class of hydroxyl polymer, such as a starch hydroxylpolymer.

Nonlimiting Example of a Process for Making a Hydroxyl Polymer Structure

Any suitable process known to those skilled in the art can be used toproduce the polymer composition and/or to polymer process the polymercomposition and/or to produce the polymer structure of the presentinvention. Nonlimiting examples of such processes are described inpublished applications: EP 1 035 239, EP 1 132 427, EP 1 217 106, EP 1217 107, WO 03/066942 and U.S. Pat. No. 5,342,225.

a. Making a Polymer Composition

In one example, a polymer composition according to the presentinvention, comprises a first class of polymers and a second class ofpolymers. The first class of polymers, which in this example comprisesabout 50:50 dry weight ratio of two different starches, comprises anacid thinned dent corn starch hydroxyl polymer (for example Eclipse®G—commercially available from A.E. Staley) and an ethoxylated cornstarch hydroxyl polymer (for example Ethylex® 2035—commerciallyavailable from A.E. Staley) and the second class of polymers comprises apolyvinyl alcohol hydroxyl polymer (for example Celvol® 310—commerciallyavailable from Celanese). In addition to the hydroxyl polymers, thepolymer composition comprises an alkaline agent, (for example sodiumhydroxide), a cationic agent (for example Arquad® 12-37-commerciallyavailable from Akzo Nobel), a crosslinking system comprising acrosslinking agent as described herein, and a crosslinking facilitator(for example ammonium chloride). Further, the polymer compositioncomprises a plasticizer (for example water). A sufficient amount ofwater is added the polymer composition such that the polymer compositionexhibits a Capillary Number of at least 1.

A polymer composition of the present invention may be prepared using ascrew extruder, such as a vented twin screw extruder.

A barrel 10 of an APV Baker (Peterborough, England) twin screw extruderis schematically illustrated in FIG. 1A. The barrel 10 is separated intoeight zones, identified as zones 1-8. The barrel 10 encloses theextrusion screw and mixing elements, schematically shown in FIG. 1B, andserves as a containment vessel during the extrusion process. A solidfeed port 12 is disposed in zone 1 and a liquid feed port 14 is disposedin zone 1. A vent 16 is included in zone 7 for cooling and decreasingthe liquid, such as water, content of the mixture prior to exiting theextruder. An optional vent stuffer, commercially available from APVBaker, can be employed to prevent the polymer composition from exitingthrough the vent 16. The flow of the polymer composition through thebarrel 10 is from zone 1 exiting the barrel 10 at zone 8.

A screw and mixing element configuration for the twin screw extruder isschematically illustrated in FIG. 1B. The twin screw extruder comprisesa plurality of twin lead screws (TLS) (designated A and B) and singlelead screws (SLS) (designated C and D) installed in series. Screwelements (A-D) are characterized by the number of continuous leads andthe pitch of these leads.

A lead is a flight (at a given helix angle) that wraps the core of thescrew element. The number of leads indicates the number of flightswrapping the core at any given location along the length of the screw.Increasing the number of leads reduces the volumetric capacity of thescrew and increases the pressure generating capability of the screw.

The pitch of the screw is the distance needed for a flight to completeone revolution of the core. It is expressed as the number of screwelement diameters per one complete revolution of a flight. Decreasingthe pitch of the screw increases the pressure generated by the screw anddecreases the volumetric capacity of the screw.

The length of a screw element is reported as the ratio of length of theelement divided by the diameter of the element.

This example uses TLS and SLS. Screw element A is a TLS with a 1.0 pitchand a 1.5 length ratio. Screw element B is a TLS with a 1.0 pitch and a1.0 L/D ratio. Screw element C is a SLS with a ¼ pitch and a 1.0 lengthratio. Screw element D is a SLS and a ¼ pitch and a ½ length ratio.

Bilobal paddles, E, serving as mixing elements, are also included inseries with the SLS and TLS screw elements in order to enhance mixing.Various configurations of bilobal paddles and reversing elements F,single and twin lead screws threaded in the opposite direction, are usedin order to control flow and corresponding mixing time.

In zone 1, a first hydroxyl polymer (for example dent corn starch)and/or first hydroxyl polymer composition (for example dent corn starchand an ethoxylated starch) is fed into the solid feed port at a rate of183 grams/minute using a K-Tron (Pitman, N.J.) loss-in-weight feeder. Asecond hydroxyl polymer and/or second hydroxyl polymer composition isfed into the same port via a second K-tron feeder at a rate of 38grams/minute.

Optionally the second hydroxyl polymer and/or second hydroxyl polymercomposition may be prepared separately and added as a water-basedpolymer composition according to the following procedure. The secondhydroxyl polymer and/or second hydroxyl polymer composition is preparedin a scraped wall reaction vessel (Chemplant Stainless Holdings Ltd.Dalton, England). The reaction vessel is capable of heating through anoil jacket and may be pressurized to prevent water loss at elevatedtemperatures. Water, an external plasticizer, is introduced into thevessel and while stirring the second hydroxyl polymer (for examplepolyvinyl alcohol) is added, optionally another hydroxyl polymer (forexample an ethoxylated starch) may also be added during this step.Additional components such as surfactants or alkaline materials such assodium/ammonium hydroxide may be added. The additive port of thereaction vessel is then closed, sealed and pressurized to 20 psi. Thereaction vessel is then heated to about 110° C. while stirring forapproximately one hour and then is pressure fed through supply lines toa B9000 pump (available from Zenith, a Division of Parker Hannafin) formetered feeding into the zone 1 of the extruder, as previouslydescribed. Adjustments are made to the feed rates to keep the totalpolymer addition to about 220 grams/minute and the water to about 136grams/minute.

The first hydroxyl polymer and/or first hydroxyl polymer composition andthe second hydroxyl polymer and/or second hydroxyl polymer compositionare combined inside the extruder (zone 1) with the water, an externalplasticizer, added at the liquid feed at a rate of 136 grams/minuteusing a Milton Roy (Ivyland, Pa.) diaphragm pump (1.9 gallon per hourpump head) to form a third hydroxyl polymer composition. The thirdhydroxyl polymer composition is then conveyed down the barrel of theextruder and cooked, in the presence of an alkaline agent, such asammonium hydroxide and/or sodium hydroxide. (introduction of externalplasticizer such as glycerin) The cooking causes a hydrogen from atleast one hydroxyl moiety on one or more of the hydroxyl polymers tobecome disassociated from the oxygen atom of the hydroxyl moiety andthus creates a negative charge on the oxygen atom of the former hydroxylmoiety. This oxygen atom is now open for substitution by a substitutionagent, such as a cationic agent, such as a quaternary ammonium compound,for example a quaternary amine.

Table 1 describes the temperature, pressure, and corresponding functionof each zone of the extruder.

TABLE 1 Temp. Description Zone (° F.) Pressure of Screw Purpose 1 70 LowFeeding/Conveying Feeding and Mixing 2 70 Low Conveying Mixing andConveying 3 70 Low Conveying Mixing and Conveying 4 130 LowPressure/Decreased Conveying and Heating Conveying 5 300 Medium PressureGenerating Cooking at Pressure and Temperature 6 250 High ReversingCooking at Pressure and Temperature 7 210 Low Conveying Cooling andConveying (with venting) 8 210 Low Pressure Generating ConveyingAfter the third hydroxyl polymer composition exits the extruder, part ofthe polymer composition can be dumped and another part (100 g) can befed into a Zenith®, type PEP II (Sanford N.C.) and pumped into a SMXstyle static mixer (Koch-Glitsch, Woodridge, Ill.). The static mixer isused to combine additional additives such as crosslinking agents,crosslinking facilitators, external plasticizers, such as water, withthe third hydroxyl polymer composition. The additives are pumped intothe static mixer via PREP 100 HPLC pumps (Chrom Tech, Apple ValleyMinn.). These pumps provide high pressure, low volume additioncapability. The third hydroxyl polymer composition of the presentinvention exhibits a Capillary Number of at least 1 and thus, is readyto be polymer processed into a polymer structure.b. Polymer Processing the Polymer Composition into a Polymer Structure

The polymer processable hydroxyl polymer composition is then polymerprocessed into a hydroxyl polymer structure, such as a fiber.Nonlimiting examples of polymer processing operations include extrusion,molding and/or fiber spinning. Extrusion and molding (either casting orblown), typically produce films, sheets and various profile extrusions.Molding may include injection molding, blown molding and/or compressionmolding. Fiber spinning may include spunbonding, melt blowing,continuous fiber producing and/or tow fiber producing. Fiber spinningmay be dry spinning or wet spinning. Polymer structures produced as aresult of polymer processing of a polymer composition in accordance withthe present invention may be combined, such as when the polymerstructures are in the form of fibers, into a fibrous structure bycollecting a plurality of the fibers onto a belt or fabric.

A polymer structure and/or fibrous structure of the present inventionmay then be post-processed by subjecting the web to a post-processingoperation. Nonlimiting examples of post processing operations includecuring, embossing, thermal bonding, humidifying, perfing, calendering,printing, differential densifying, tuft deformation generation, andother known post-processing operations.

c. Post-Processing the Fibrous Structure

As shown in FIG. 2, in one example, a fibrous structure 18 formed byprocessing the polymer composition according to the present inventioninto a plurality of fibers is subjected to a post-processing operation20.

The fibrous structure 18 of the present invention may be cured during acuring operation 22 during which the fibrous structure 18 exhibits atemperature of from about 110° C. to about 260° C. and/or from about110° C. to about 240° C. and/or from about 110° C. to about 215° C.and/or from about 110° C. to about 200° C. and/or from about 120° C. toabout 195° C. and/or from about 130° C. to about 185° C. for a timeperiod of from about 0.01 and/or 1 and/or 5 and/or 15 seconds to about60 minutes and/or from about 20 seconds to about 45 minutes and/or fromabout 30 seconds to about 30 minutes. In one example, the curingoperation 22 comprises passing the fibrous structure 18 over curingplates (not shown) set at about 135° C. to about 155° C. Alternativecuring operations include radiation methods such as UV, e-beam, IR andother temperature-raising methods.

It has been found that time (i.e., residence time—the length of timethat the fibrous structure is imparted a temperature capable of curingthe fibrous structure and/or materials within the fibrous structure) andthe curing temperature can be adjusted. For example, if the fibrousstructure is at a temperature suitable for curing for a relatively longperiod of time, then a lower curing temperature may be used to obtaincuring. However, if the fibrous structure is at a temperature suitablefor curing for a relatively short period of time, then a higher curingtemperature may need to be used to obtain curing.

In addition to the curing operation 22, the fibrous structure 18 may bethermally bonded during a thermal bonding operation 24. The thermalbonding operation 24 may occur prior to, simultaneous with and/or afterthe curing operation 22. During the thermal bonding operation 24, thecured fibrous structure 18′ is imparted properties including atemperature above the Tg of at least one of the polymers within thepolymer structure, especially within the polymer structure fiber withinthe fibrous structure 18′. In one example, the conditions includeimparting to the fibrous structure 18′ a temperature in the presence ofhumidity such that the temperature of the fibrous structure is above theTg of at least one of the polymers of the polymer structure fiber withinthe fibrous structure 18′. In other words, the fibrous structure 18′ isimparted a temperature with or without additional humidity in the rangeof from about 110° C. to about 200° C. and/or from about 120° C. toabout 195° C. and/or from about 130° C. to about 185° C. During thethermal bonding operation 24, a physical pattern, such as a non-randomrepeating pattern, of discrete thermally bonded regions 26, continuousnetwork (not shown) or discontinuous network (not shown) may be createdin the fibrous structure 18″ as a result of the fibrous structure 18′contacting a pattern delivering object, such as a patterned roll 28. Atthe patterned roll 28, the fibrous structure 18′ is subjected to apressure of at least about 5 pounds/linear inch (“pli”) and/or at leastabout 20 pli and/or at least about 50 pli and/or at least about 200 pliand/or at least about 250 pli and/or at least about 300 pli. In oneexample, the fibrous structure 18′ is subjected to a pressure of atleast about 350 pli. In one example, the fibrous structure 18′ travelsthrough a nip 30 created by a patterned roll 28 and an anvil roll 32with a 0 mils gap.

In another example (not shown), a physical pattern may be created in thefibrous structure as a result of contacting the fibrous structure withan adhesive agent, such as latex, in a physical pattern of discreteregions, continuous network and/or discontinuous network. Delivery ofthe adhesive agent onto the fibrous structure may be performed by anysuitable means, such as by slot extrusion, gravure roll printing, inkjet printing and other suitable means known in the art. During thecontacting of the adhesive agent to the fibrous structure, the fibrousstructure may be imparted an appropriate temperature for thermal bondingas described above concurrently and/or subsequent to the adhesive agentcoming into contact with the fibrous structure.

After the fibrous structure has been subjected to a thermal bondingoperation, the fibrous structure, as shown in FIG. 3 comprises anunfused region 34 and a fused region 36, which corresponds to thethermally bonded regions 26 created in the fibrous structure during thethermal bonding operation as shown in FIG. 2.

As shown in FIGS. 3 and 4, a thermally bonded fibrous structure 18″comprises an unfused region 34 and a fused region 36.

As shown in FIG. 5A, a scanning electron microscope photograph showing across section of an unfused region 34 of a fibrous structure 18″ of thepresent invention, the unfused region 34 comprises separate, discretefibers 38.

As shown in FIG. 5B, a scanning electron microscope photograph showing across section of a fused region 36 of a fibrous structure 18″ of thepresent invention, the absence of separate, discrete fibers as shown inFIG. 5A, is evidenced in the fused region 36. Even though some of thefused regions may have some separate, discrete fibers, especially in thecase of less than perfect thermal bonding operation conditions, the factthat some of the fibers within the fibrous structure are fused togetherinto a unitary structure evidences a fused region and/or a transitionregion between an unfused region and a fused region.

Once a fibrous structure 18″ has been subjected to a thermal bondingoperation, the fibrous structure 18″ may be subjected to additionalpost-processing operations in order to improve additional physicalproperties of the fibrous structure 18″. Nonlimiting examples of theseadditional physical properties include softness, appearance, lintingand/or pilling.

As shown in FIG. 6, nonlimiting examples of additional post-processingoperations include subjecting the fibrous structure 18″ to a hyperbaricdeflection process and/or an embossing process, such as a heatedembossing process. In one example, the fibrous structure 18″ mustcontain enough moisture to permit deformation of the fibrous structure18″ without tearing the fibrous structure 18″ during the post-processingoperation. In one example, the fibrous structure 18″ comprises fromabout 8% to about 20% and/or from about 10% to about 18% and/or fromabout 12% to about 17% and/or from about 14% to about 16% surfacemoisture as measured by IR. One means of ensuring appropriate moisturewithin the fibrous structure 18″ is by passing the fibrous structure 18″through a humidity chamber 40 at about 85% relative humidity and 110° C.to 120° C. A vacuum box can pull moisture through the web. The humidityfrom the humidity chamber 40 plasticizes the fibrous structure 18″ toproduce a plasticized fibrous structure 18′″. When the plasticizedfibrous structure 18′″ exits the humidity chamber 40, the plasticizedfibrous structure 18′″ then passes through a nip 42 formed by apatterned embossing roll 44 and a rubber roll 46 at a nip pressure of atleast about 1 pli and/or at least about 5 pli and/or at least about 10pli and/or at least about 20 pli to form fibrous structure 18″″. Inaddition to contacting the rubber roll 46, the fibrous structure 18′″may contact a heated anvil roll (not shown) while the fibrous structure18′″ is still in contact with the patterned embossing roll 44. Theheated anvil roll is heated from about 30° C. to about 200° C. and/orfrom about 35° C. to about 180° C. and/or from about 40° C. to about140° C. and/or from about 40° C. to about 125° C. For example, heatingthe anvil roll to about 66° C. gives the anvil roll surface atemperature of about 40° C. The nip pressure between the patternedembossing roll 44 and the anvil roll, when present, is at least about 1pli and/or at least about 5 pli and/or at least about 10 pli and/or atleast about 20 pli.

In another example, the fibrous structure, even in the absence of beingsubjected to a thermal bonding operation, may exhibit a humidity, whichmay be imparted to the fibrous structure as a result of a humiditychamber as described above, and may exhibit a temperature above the Tg(for example above about 60° C.) of at least one of the hydroxylpolymers within the hydroxyl polymer fibers of the fibrous structurewhile the fibrous structure is imparted a pattern via a patterned beltan a rubber roll or anvil roll to impart a pattern to the fibrousstructure. The resulting fibrous structure may have a CETM*L² Factorthat is less than 950.

Additional post-processing operations may be performed on the fibrousstructure, such as tuft-generating processes, printing processes,chemical softening processes, folding processes, calendaring processesand the like.

After post-processing the fibrous structure, the fibrous structure canthen be wound on cores or wound without cores.

Two or more plies of the fibrous structure may be combined, with orwithout ply bond glue, to form a multi-ply sanitary tissue product.

As shown in FIG. 7, a fibrous structure 18 (Stage A) is post-processedby subjecting the fibrous structure 18 to a curing operation andsubsequently to a thermal bonding operation to produce a thermallybonded fibrous structure 18″ (Stage B). The thermally bonded fibrousstructure 18″ (Stage B) is then further post-processed by subjecting thefibrous structure 18″ (Stage B) to a humidity chamber and subsequentlyto a hyperbaric deflection operation to produce fibrous structure 18′″(Stage C). Substantially contemporaneous (simultaneously orsubstantially simultaneously) with the hyperbaric deflection operation,the fibrous structure 18″ (Stage D) may be contacted by a heated anvilroll to produce fibrous structure 18″″.

Nonlimiting Examples Example 1

A two-ply sanitary tissue product comprising two individually formedabout 24 gsm fibrous structures that is made from a polymer compositioncomprising 17% polyvinyl alcohol, 34.3% Eclipse G starch, 36.3% Ethylex2035 starch, 0.7% Arquad® 12-37, 0.65% ammonium hydroxide, 3.95%ammonium chloride and 7.4% crosslinking agent. The fibrous structuresare prepared according to the present invention wherein each fibrousstructure is subjected to a thermal bonding operation and are curedsimultaneous with the thermal bonding operation or are cured later inthe process. After each fibrous structure is subjected to the thermalbonding operation, the fibrous structures are married to one another toform a 2-ply fibrous structure and are humidified. After humidification,the 2-ply fibrous structure is then subjected to a hyperbaric deflectionprocess and then a heated emboss process. After and/or during the heatedemboss process the 2-plies are heat sealed together and then wound up toform the 2-ply sanitary tissue product. The 2-ply sanitary tissueproduct exhibits an ITWT of 89.9 g/inch, a Dry Burst Energy of 4.84(grams_(force)×cm)/cm² and a Dry Lint Score of 1.5. Therefore, the 2-plysanitary tissue product exhibits a CETM Factor of 15.24 and a CETM*L²Factor of 35.98.

Example 2

A single-ply sanitary tissue product comprising one about 48 gsm fibrousstructure that is made from the polymer composition of Example 1. Thefibrous structure is prepared as described in Example 1 except that thefibrous structure is not married to another fibrous structure and thus,is not heat sealed. The single-ply sanitary tissue product exhibits anITWT of 89.9 g/inch, a Dry Burst Energy of 5.9 (grams_(force)×cm)/cm²and a Dry Lint Score of 2.3. Therefore, the single-ply sanitary tissueproduct exhibits a CETM Factor of 15.24 and a CETM*L² Factor of 80.61.

Example 3

A Comparative Example of a single-ply sanitary tissue product that doesnot exhibit a CETM Factor nor a CETM*L² Factor within the scope of thepresent invention. The single-ply sanitary tissue product comprises oneabout 49 gsm fibrous structure made from a polymer compositioncomprising 90% Penfilm 162 starch (available from Penford), 10% Caliberl82 (available from Cargill), 3.6% crosslinking agent, 0.7% ammoniumcitrate and 1.7% DL233 modified latex (available from The Dow ChemicalCompany). The fibrous structure is according to the present invention.However, unlike Examples 1 and 2, the fibrous structure is not subjectedto a thermal bonding operation, rather the fibrous structure ishumidified at room temperature (about 73° F.±4° F. (about 23° C.±2.2°C.)) and pressed into a patterned belt to impart a pattern to thefibrous structure. The fibrous structure is then wound up. Thesingle-ply sanitary tissue product exhibits an ITWT of 37.7 g/inch, aDry Burst Energy of 1.13 (grams_(force)×cm)/cm² and a Dry Lint Score of7.5. Therefore, the single-ply sanitary tissue product exhibits a CETMFactor of 33.36 and a CETM*L² Factor of 1876.50.

Example 4

A single-ply sanitary tissue product comprising one about 49 gsm fibrousstructure that is made from the polymer composition of Example 1. Thefibrous structure is prepared without being subjected to a thermalbonding operation and/or a hyperbaric deflection process nor a heatedemboss process, rather the fibrous structure is subjected to a humidconsolidation process which humidifies the fibrous structure, subjectsthe fibrous structure to a temperature above the Tg of the polyvinylalcohol and imparts a pattern to the fibrous structure. The fibrousstructure is then embossed via steel-to-steel emboss rolls. Thesingle-ply sanitary tissue product exhibits an ITWT of 103.3 g/inch, aDry Burst Energy of 3.1 (grams_(force)×cm)/cm² and a Dry Lint Score of5. Therefore, the single-ply sanitary tissue product exhibits a CETM*L²Factor of 833.

Test Methods

Unless otherwise indicated, all tests described herein including thosedescribed under the Definitions section and the following test methodsare conducted on samples that have been conditioned in a conditionedroom at a temperature of 73° F.±4° F. (about 23° C.±2.2° C.) and arelative humidity of 50%±10% for 24 hours prior to the test. Further,all tests are conducted in such conditioned room. Tested samples andfelts should be subjected to 73° F.±4° F. (about 23° C.±2.2° C.) and arelative humidity of 50%±10% for 24 hours prior to testing.

A. Initial Total Wet Tensile Test Method

The initial total wet tensile of polymer structures and/or fibrousstructures and/or sanitary tissue products of the present invention isdetermined using a Thwing-Albert EJA Material Tester Instrument, Cat.No. 1350, equipped with 5000 g load cell available from Thwing-AlbertInstrument Company, 14 Collings Ave. W. Berlin, N.J. 08091.10% of the5000 g load cell is utilized for the wet tensile test.

i. Sample Preparation

A strip of sample to be tested [2.54 cm (1 inch) wide by greater than5.08 cm (2 inches) long is obtained.

ii. Operation

The test settings for the instrument are:

Crosshead speed—10.16 cm/minute (4.0 in/minute)

Initial gauge length—2.54 cm (1.0 inch)

Adjust the load cell to read zero plus or minus 0.5 grams_(force).

iii. Testing Samples

One end of the sample strip is placed between the upper jaws of themachine and clamped. After verifying that the sample strip is hangingstraight between the lower jaws, clamp the other end of the sample stripin the lower jaws.

a. Pre-Test

Strain the sample strip to 25 grams_(force) (+/−10 grams_(force)) at astrain rate of 3.38 cm/minute (1.33 in/minute) prior to wetting thesample strip. The distance between the upper and lower jaws now beinggreater than 2.54 cm (1.0 inch). This distance now becomes the newzero-strain position for the forthcoming wet test.

b. Wet Test

While the sample strip is still at 25 grams_(force) (+/− 10grams_(force)), it is wetted, starting near the upper jaws, a water/0.1%Pegosperse® ML200 (available from Lonza Inc. of Allendale, N.J.)solution [having a temperature of about 73° F.±4° F. (about 23° C.±2.2°C.)] is delivered to the sample strip via a 2 ml disposable pipet. Donot contact the sample strip with the pipet and do not damage the samplestrip by using excessive squirting pressure. The solution iscontinuously added until the sample strip is visually determined to becompletely saturated between the upper and lower jaws. At this point,the load cell is re-adjusted to read zero plus or minus 0.5grams_(force).

The sample strip is then strained at a rate of 10.16 cm/minute (4inches/minute) and continues until the sample strip is strained past itsfailure point (failure point being defined as the point on theforce-strain curve where the sample strip falls to 50% of its peakstrength after it has been strained past its peak strength). Thestraining of the sample strip is initiated between 5-10 seconds afterthe sample is initially wetted. The initial result of the test is anarray of data points in the form of load (grams_(force)) versus strain(where strain is calculated as the crosshead displacement (cm of jawmovement from starting point) divided by the initial separation distance(cm) between the upper and lower jaws after the pre-test.

The sample is tested in two orientations, referred to here as MD(machine direction, i.e., in the same direction as the continuouslywound reel and forming fabric) and CD (cross-machine direction, i.e.,90° from MD). The MD and CD wet tensile strengths are determined usingthe above equipment and calculations in the following manner:ITWT(g _(f)/inch)=Peak Load_(MD)(g _(f))/1(inch_(width))+PeakLoad_(CD)(g _(f))/1(inch_(width))

The ITWT value as used herein is the normalized ITWT value calculated asfollows: Normalized {ITWT}={ITWT}*50 (g/m²)/Basis Weight of Strip(g/m²).

B. Dry Burst Energy Test Method

The dry burst energy of polymer structures and/or fibrous structuresand/or sanitary tissue products of the present invention is determinedusing a Thwing-Albert EJA Material Tester Instrument, Cat. No. 1350,equipped with 2000 g load cell, and ⅝ inch diameter stainless steelplunger available from Thwing-Albert Instrument Company, 14 CollingsAve. W. Berlin, N.J. 08091.

i. Sample Preparation

A strip of sample to be tested [11.43 cm (4.5 inches) wide by 25.4 cm(10 inches)] long is obtained. The sample strip should have an untaintedcircular-shaped portion that is larger in area (greater than 65 m²) thanthe circular area inside of the sample holder rings (62.1 cm²) of theapparatus. “Untainted” as used herein means that the portion does nothave perforations or significantly more pinholes than other portions ofthe sample strip nor does it have any tape and/or adhesive present onthe surface of the portion of the sample strip. Do not stretch, wrinkle,or overly handle the sample strip, especially in the portion of thesample strip that will be contacted by the plunger.

ii. Operation

The test settings for the instrument are:

Plunger Speed—12.7 cm/minute

Plunger Acceleration—12 cm/second²

Inner Diameter of Sample Holder Rings—8.89 cm

Sample Data Acquisition Rate—80 data points/second

Adjust the load cell to read zero plus or minus 1 grams_(force).

In order to move the plunger to the correct zero base position, place aflat, metal ruler or plate in the sample test position (where a samplenormally would go), then use the up and down control buttons to positionthe plunger just below where it touches the ruler. Watch the load cellreading to signal when the ruler is in contact with the plunger. Lowerthe plunger in 0.01 cm increments until the load cell reading returns tozero level, then set this position as the new zero position.

Prior to operation, the instrument load cell calibration is verifiedusing a 50 gram weight. Be sure nothing abnormal is touching the plungerand load cell, then zero the load cell reading. Carefully place the 50gram weight on top the plunger. Record the load cell reading into theappropriate log sheet in the binder. If outside the acceptable range,discontinue testing and contact the lab owner and/or Thwing-AlbertCompany for recalibration.

iii. Testing Samples

Place the sample on the lower ring of the sample holding device with theouter surface of the product facing up, so the sample completely coversthe open surface of the sample holding ring and a small amount of sampleextends out to the sides of the solid metal surface. If perforations arepresent, be sure that they are outside the open center-area of the ring.After the sample strip is properly in place on the lower ring, lower theupper ring of the pneumatic holding device. The sample to be tested isnow securely gripped in the sample holding unit.

Push the START button. The plunger will begin to rise. At some point,the sample will begin to tear or “burst”. NOTE: In unusual cases,because of very high sample stretch, the sample may not burst within thegiven test unit's range of capability. Report these cases with notation“Did Not Burst”.

After the plunger reaches its maximum elevation, it will automaticallyreverse and return to its original position. After the plunger hasreturned to its original position, raise the upper ring, and remove thetested sample portion. Another sample strip portion is placed on thelower ring of the sample holding assembly and clamped in place. Thissequence is continued until four testable portions of a particularsample strip have been tested. NOTE: During a series of tests, theinstrument ZERO should be checked—adjust accordingly if outside theacceptable range of 0±1 gram.

iv. Calculations

Dry Burst Energy is calculated by calculating the area under the forceversus plunger displacement curve (from 0 displacement to peak loaddisplacement point) created by the data captured by the instrument for asample tested divided by the total sample area inside thecircular-shaped clamp (62.1 cm²). Dry Burst Energy is reported to thenearest 0.01 (grams_(force)*cm)/cm². The four values obtained from onesample strip are averaged to give the reported value.

C. Lint/Pilling Test Method

i. Sample Preparation

Sample strips (a total of 4 if testing both sides, 2 if testing a singleside) of fibrous structures and/or sanitary tissue products, which donot have abraded portions) 11.43 cm (4.5 inch) wide×30.48 cm to 40.64 cm(12-16 inch) long such that each sample strip can be folded upon itselfto form a 11.43 cm (4.5 inch) wide (CD) by 10.16 cm (4.0 inch) long (MD)rectangular implement having a total basis weight of between 140 to 200g/m² are obtained and conditioned according to Tappi Method #T402OM-88.For both side testing, makeup two rectangular implements as describedabove with a first side out and then two rectangular implements with theother side out (keep track of which are which).

For sanitary tissue products formed from multiple plies of fibrousstructure, this test can be used to make a lint measurement on themulti-ply sanitary tissue product, or, if the plies can be separatedwithout damaging the sanitary tissue product, a measurement can be takenon the individual plies making up the sanitary tissue product. If agiven sample differs from surface to surface, it is necessary to testboth surfaces and average the scores in order to arrive at a compositelint score. In some cases, sanitary tissue products are made frommultiple-plies of fibrous structures such that the facing-out surfacesare identical, in which case it is only necessary to test one surface.

Each sample is folded upon itself to make a 4.5″ CD×4″ MD sample. Fortwo-surface testing, make up 3 (4.5″ CD×4″ MD) samples with a firstsurface “out” and 3 (4.5″ CD×4″ MD) samples with the second surface“out”. Keep track of which samples are first surface “out” and which aresecond surface “out”.

For a dry lint/pilling test, obtain a 30″×40″ piece of Crescent #300cardboard from Cordage Inc. (800 E. Ross Road, Cincinnati, Ohio, 45217).Using a paper cutter, cut out six pieces of cardboard of dimensions of6.35 cm×15.24 cm (2.5 inch×6 inch). Puncture two holes into each of thesix pieces of cardboard by forcing the cardboard onto the hold down pinsof the Sutherland Rub tester. Center and carefully place each of thecardboard pieces on top of the previously folded samples with the testedside exposed outward. Make sure the 15.24 cm (6 inch) dimension of thecardboard is running parallel to the machine direction (MD) of each ofthe folded samples. Fold one edge of the exposed portion of the sampleonto the back of the cardboard. Secure this edge to the cardboard withadhesive tape obtained from 3M Inc. (¾″ wide Scotch Brand, St. Paul,Minn.). Carefully grasp the other over-hanging tissue edge and snuglyfold it over onto the back of the cardboard. While maintaining a snugfit of the sample onto the cardboard, tape this second edge to the backof the cardboard. Repeat this procedure for each sample. Turn over eachsample and tape the cross direction edges of the sample to thecardboard. One half of the adhesive tape should contact the sample whilethe other half is adhering to the cardboard. Repeat this procedure foreach of the samples. If the sample breaks, tears, or becomes frayed atany time during the course of this sample preparation procedure, discardand make up a new sample with a sample strip.

For a wet lint/pilling test, first prepare the testing surface bysecurely fastening a smooth surface foam pad (⅛″ thick, Poron quickRecovery Foam, adhesive back, firmness rating 13), having a lengthgreater than or equal to 15.24 cm (6 inch) and a width greater than orequal to 12.70 cm (5 inch), to a flat and level table surface,positioned in such a way that its ≧12.70 cm length direction is parallelto the table edge, and is flush with the table edge. On top of this foamsurface, adhere a piece of fine grade sandpaper (12.70 cm×15.24 cm,using double-sided tape or glue), with its shorter axis parallel to thetable edge, and centered with respect to other dimensions of the foam.Position the folded sample such that one of its CD-axis sides is 0¼ inchfrom the from the table surface and foam/sandpaper edge. Adhere theopposite edge of the sample (using ≧8″ length of Scotch brand ¾ inchtransparent tape) with tape extending long enough to adhere to bothsides of the table.

ii. Felt and Weight Component Preparation

Cut a piece of a black test felt (F-55 or equivalent from New EnglandGasket, 550 Broad Street, Bristol, Conn. 06010) to the dimensions of2¼″×7¼″. The felt is to be used in association with a weight. The weightmay include a clamping device to attach the felt/cardboard combinationto the weight. The weight and any clamping device total five (5) pounds.The weight is available from Danilee Company, San Antonio, Tex., and isassociated with the Sutherland Rub Tester. The weight has a 2″×4″ pieceof smooth surface foam attached to its contact face (⅛″ thick, Poronquick Recovery Foam, adhesive back, firmness rating 13). For the drytest, the felt is clamped directly against this foam surface, providingan effective contact area of 8 in² and a contact pressure of about 0.625psi. For the wet test, an additional 1″×4″ foam strip (same foam asdescribed above) is attached and centered in the length direction on topthe 2″×4″ foam strip, thus, after clamping the felt against thissurface, an effective contact area of 4 in² and a contact pressure ofabout 1.25 psi is established. Also, for the wet test only, afterclamping the felt to weight apparatus, two strips of tape (4¼″-5¼″ inlength, Scotch brand ¾″ width) are placed along each edge of the felt(parallel to the long side of the felt) on the felt side that will becontacting the sample. The untaped felt between the two tape strips hasa width between 18-21 mm. Three marks are placed on one of the strips oftape at 0, 4 and 10 centimeters along the flat, test region of the testfelt.

iii. Conducting Dry Lint/Pills Test

The amount of dry lint and/or dry pills generated from a fibrous productaccording to the present invention is determined with a Sutherland RubTester (available from Danilee Company, San Antonio, Tex.). This testeruses a motor to rub a felt/weight component 5 times (back and forth)over the fibrous product, while the fibrous product is restrained in astationary position.

First, turn on the Sutherland Rub Tester pressing the “reset” button.Set the tester to run 5 strokes at the lower of the two speeds. Onestroke is a single and complete forward and reverse motion of theweight. The end of the rubbing block should be in the position closestto the operator at the beginning and at the end of each test.

Place the sample/cardboard combination on the base plate of the testerby slipping the holes in the board over the hold-down pins. Thehold-down pins prevent the sample from moving during the test. Hook thefelt/weight combination into the tester arm of the Sutherland RubTester, and gently place it on top of the sample/cardboard combination.The felt must rest level on the calibration sample and must be in 100%contact with the calibration sample surface (use a bubble levelindicator to verify). Activate the Sutherland Rub Tester by pressing the“start” button.

Keep a count of the number of strokes and observe and make a mental noteof the starting and stopping position of the felt covered weight inrelationship to the sample. If the total number of strokes is five andif the position of the calibration felt covered weight is the same atthe end as it was in the beginning of the test, the test was successfulperformed. If the total number of strokes is not five or if the startand end positions of the felt covered weight are different, then theinstrument may require servicing and/or recalibration.

Once the instrument is finished moving, remove the felt covered weightfrom the holding arm of the instrument, and unclamp the felt from theweight. Lay the test felt on a clean, flat surface.

iv. Conducting Wet Lint/Pills Test

Wet lint/pills are determined by pulling, during one pass, a partiallywetted felt/weight component over a sample.

To wet the felt, pipette 0.6 ml of deionized water on to the felt,between the 0 and 4 cm marks, as represented on the tape attached to thefelt. Before the water soaks into the felt, use a metal ruler with awidth of ¾″, to spread the water uniformly across the 0-4 cm marked wetzone without spilling onto the tape or into the dry zone (between the 4and 10 cm marks).

After the water is uniformly distributed and fully penetrated into thefelt (not beaded up at all), place weight-felt apparatus on the samplesuch that the felt wetted region is ≦¼″ from the edge of sample andtape. After approximately one second, pull the knob horizontally untilthe apparatus is completely off the table—the pulling process shouldtake 0.5 to 1.5 seconds. Pull the weight in a manner to avoid placingany additional force on the felt/weight component other than thehorizontal pull force. The pulling process should occur as asubstantially continuous or continuous motion. Record if sample sheettears significantly due to felt rubbing, and/or if pieces fall off (ontofloor) during the test.

Carefully remove the felt from the weight, store in a safe, flat place,and allow to dry before imaging (≧24 hours, standard conditions). Do notstack multiple layers of felt on top one another to prevent sticking andlint/pill transfer.

The next step is to complete image capture, analysis, and calculationson the test felts as described below.

vi. Image Capture

The images of the felt (untested), sample (untested) and felt (tested)are captured using a computer and scanner (Microtek ArtixScan 1800f). Becertain that scanner glass is clear and clean. Place felts centered onscanner, face down. Adjust image capture boundaries so that all feltsare included into the captured image. Set-up the scanner to 600 dpi,RGB, and 100% image size (no scaling). After successfully imaging thefelts, save the image as an 8-bit RGB TIFF image, remove felts fromscanner, and repeat from process until all felts images are captured.

Additional images of the sample (untested) may need to be captured (inthe same manner) if they have an average luminance (using Optimassoftware) significantly less than 254 (less than 244), after beingconverted to an 8-bit gray-scale image. Also, an image of a known lengthstandard (e.g., a ruler) is taken (exposure difference does not matterfor this image). This image is used to calibrate the image analysissoftware distance scale.

vii. Image Analysis

The images captured are analyzed using Optimas 6.5 Image Analysissoftware commercially available from Media Cybernetics, L.P. Imagingset-up parameters, as listed herein, must be strictly adhered to inorder to have meaningfully comparative lint score and pill scoreresults.

First, an image with a known length standard (e.g., a ruler) is broughtup in Optimas, and used to calibrate length units (millimeters in thiscase). For dry testing, the region of interest (ROI) area isapproximately 4500 mm2 (90 mm by 50 mm), and the wetted and dragged ROIarea is approximately 1500 mm2 (94 mm by 16 mm). The exact ROI area ismeasured and recorded (variable name: ROI area). The average gray valueof the unrubbed region of the test felt is used as the baseline, and isrecorded for determining the threshold and lint values (variable name:untested felt GV avg). It is determined by creating a region of interestbox (ROI) with dimensions approximately 5 mm by 25 mm on the untested,unrubbed area of the black felt, on opposite ends of the rubbed region.The average of these two average gray value luminaces for each of theROI's is used as the untested felt GV average value for that particulartest felt. This is repeated for all test felts analyzed. The test sheetluminance is typically near saturated white (gray value 254) and fairlyconstant for samples of interest. If believed to be different, measurethe test sheet in a similar fashion as was done for the untested felt,and record (variable name=untested sheet GV avg). The luminancethreshold is calculated based on the untested felt GV avg and untestedsheet GV avg as follows:

For the dry lint/pilling test felts:(untested_sheet_(—) GV _(—) avg−untested_felt_(—) GV _(—)avg)*0.4+untested_felt_(—) GV _(—) avg

For the wet lint/pilling test felts:(untested_sheet_(—) GV _(—) avg−untested_felt_(—) GV _(—)avg)*0.25+untested_felt_(—) GV _(—) avg

The test felt image is opened, and the ROI and its boundaries arecreated and properly positioned to encompass a region that completelycontains pills and contains the highest concentration of pills on therubbed section of the test felt. The average luminance for the ROI isrecorded (variable name: ROI GV avg). Pills are determined as follows:Optimas creates boundary lines in the image where pixel luminance valuescross through the threshold value (e.g., if the threshold is 120,boundary lines are created where pixels of higher and lower value existon either side. The criteria for determining a pill is that it must havean average luminance greater than the threshold value, and have aperimeter length greater than 0.5 mm. The sum of the pilled areasvariable name is: Total Pilled Area.

Measurement data of the ROI, and for each pill is exported from Optimasto a spreadsheet for performing the following calculations.

viii. Calculations

The data obtained from the image analysis is used in the followingcalculations:Pilled Area %=Percent of area covered by pilling=Total Pilled Area/ROIareaLint Score=Gray value difference between unpilled area of the rubbedtest felt area and the untested feltLint Score=unpilled felt Gray Value avg−untested felt Gray Value avg

-   -   where: unpilled felt Gray Value avg=[(ROI Gray Value avg*ROI        area)−(pilled Gray Value avg*pilled area)]/Total Unpilled Area

By taking the average of the lint score of the first-side surface andthe second-side surface, the lint is obtained which is applicable tothat particular web or product. In other words, to calculate lint score,the following formula is used:

${{Dry}\mspace{14mu}{Lint}\mspace{14mu}{Score}} = \frac{{{Dry}\mspace{14mu}{Lint}\mspace{14mu}{Score}},{{1^{st}\mspace{14mu}{side}} + {{Dry}\mspace{14mu}{Lint}\mspace{14mu}{Score}}},{2^{nd}\mspace{14mu}{side}}}{2}$${{Dry}\mspace{14mu}{Pill}\mspace{14mu}{Area}\mspace{14mu}\%} = \frac{{{Dry}\mspace{14mu}{Pill}\mspace{14mu}{Area}\mspace{14mu}\%},{{1^{st}\mspace{14mu}{side}} + {{Dry}\mspace{14mu}{Pill}\mspace{14mu}{Area}\mspace{14mu}\%}},{2^{nd}\mspace{14mu}{side}}}{2}$${{Wet}\mspace{14mu}{Lint}\mspace{14mu}{Score}} = \frac{{{Wet}\mspace{14mu}{Lint}\mspace{14mu}{Score}},{{1^{st}\mspace{14mu}{side}} + {{Wet}\mspace{14mu}{Lint}\mspace{14mu}{Score}}},{2^{nd}\mspace{14mu}{side}}}{2}$${{Wet}\mspace{14mu}{Pill}\mspace{14mu}{Area}\mspace{14mu}\%} = \frac{{{Wet}\mspace{14mu}{Pill}\mspace{14mu}{Area}\mspace{14mu}\%},{{1^{st}\mspace{14mu}{side}} + {{Wet}\mspace{14mu}{Pill}\mspace{14mu}{Area}\mspace{14mu}\%}},{2^{nd}\mspace{14mu}{side}}}{2}$D. Shear Viscosity of a Polymer Composition Measurement Test Method

The shear viscosity of a polymer composition of the present invention ismeasured using a capillary rheometer, Goettfert Rheograph 6000,manufactured by Goettfert USA of Rock Hill S.C., USA. The measurementsare conducted using a capillary die having a diameter D of 1.0 mm and alength L of 30 mm (i.e., L/D=30). The die is attached to the lower endof the rheometer's 20 mm barrel, which is held at a die test temperatureof 75° C. A preheated to die test temperature, 60 g sample of thepolymer composition is loaded into the barrel section of the rheometer.Rid the sample of any entrapped air. Push the sample from the barrelthrough the capillary die at a set of chosen rates 1,000-10,000seconds⁻¹. An apparent shear viscosity can be calculated with therheometer's software from the pressure drop the sample experiences as itgoes from the barrel through the capillary die and the flow rate of thesample through the capillary die. The log (apparent shear viscosity) canbe plotted against log (shear rate) and the plot can be fitted by thepower law, according to the formula η=Kγ^(n−1), wherein K is thematerial's viscosity constant, n is the material's thinning index and γis the shear rate. The reported apparent shear viscosity of thecomposition herein is calculated from an interpolation to a shear rateof 3,000 sec⁻¹ using the power law relation.

E. Shear Viscosity Chance Test Method

Viscosities of three samples of a single polymer composition of thepresent invention are measured by filling three separate 60 cc syringes;the shear viscosity of one sample is measured immediately (initial shearviscosity) (it takes about 10 minutes from the time the sample is placedin the rheometer to get the first reading) according to the ShearViscosity of a Polymer Composition Measurement Test Method. If theinitial shear viscosity of the first sample is not within the range of5-8 Pascal·Seconds as measured at a shear rate of 3,000 sec⁻¹, then thesingle polymer composition has to be adjusted such that the singlepolymer composition's initial shear viscosity is within the range of 5-8Pascal·Seconds as measured at a shear rate of 3,000 sec⁻¹ and this ShearViscosity Change Test Method is then repeated. Once the initial shearviscosity of the polymer composition is within the range of 5-8Pascal·Seconds as measured at a shear rate of 3,000 sec⁻¹, then theother two samples are measured by the same test method after beingstored in a convection oven at 80° C. for 70 and 130 minutes,respectively. The shear viscosity at 3000 sec⁻¹ for the 70 and 130minute samples is divided by the initial shear viscosity to obtain anormalized shear viscosity change for the 70 and 130 minute samples.

F. Fiber Diameter Test Method

A polymer structure comprising fibers of appropriate basis weight(approximately 5 to 20 grams/square meter) is cut into a rectangularshape, approximately 20 mm by 35 mm. The sample is then coated using aSEM sputter coater (EMS Inc, PA, USA) with gold so as to make the fibersrelatively opaque. Typical coating thickness is between 50 and 250 nm.The sample is then mounted between two standard microscope slides andcompressed together using small binder clips. The sample is imaged usinga 10× objective on an Olympus BHS microscope with the microscopelight-collimating lens moved as far from the objective lens as possible.Images are captured using a Nikon D1 digital camera. A Glass microscopemicrometer is used to calibrate the spatial distances of the images. Theapproximate resolution of the images is 1 μm/pixel. Images willtypically show a distinct bimodal distribution in the intensityhistogram corresponding to the fibers and the background. Cameraadjustments or different basis weights are used to achieve an acceptablebimodal distribution. Typically 10 images per sample are taken and theimage analysis results averaged.

The images are analyzed in a similar manner to that described by B.Pourdeyhimi, R. and R. Dent in “Measuring fiber diameter distribution innonwovens” (Textile Res. J. 69(4) 233-236, 1999). Digital images areanalyzed by computer using the MATLAB (Version. 6.3) and the MATLABImage Processing Tool Box (Version 3.) The image is first converted intoa grayscale. The image is then binarized into black and white pixelsusing a threshold value that minimizes the intraclass variance of thethresholded black and white pixels. Once the image has been binarized,the image is skeltonized to locate the center of each fiber in theimage. The distance transform of the binarized image is also computed.The scalar product of the skeltonized image and the distance mapprovides an image whose pixel intensity is either zero or the radius ofthe fiber at that location. Pixels within one radius of the junctionbetween two overlapping fibers are not counted if the distance theyrepresent is smaller than the radius of the junction. The remainingpixels are then used to compute a length-weighted histogram of fiberdiameters contained in the image.

All documents cited in the Detailed Description of the Invention are, inrelevant part, incorporated herein by reference; the citation of anydocument is not to be construed as an admission that it is prior artwith respect to the present invention. To the extent that any meaning ordefinition of a term in this written document conflicts with any meaningor definition of the term in a document incorporated by reference, themeaning or definition assigned to the term in this written documentshall govern.

The dimensions and values disclosed herein are not to be understood asbeing strictly limited to the exact numerical values recited. Instead,unless otherwise specified, each such dimension is intended to mean boththe recited value and a functionally equivalent range surrounding thatvalue. For example, a dimension disclosed as “40 mm” is intended to mean“about 40 mm”.

While particular embodiments of the present invention have beenillustrated and described, it would be obvious to those skilled in theart that various other changes and modifications can be made withoutdeparting from the spirit and scope of the invention. It is thereforeintended to cover in the appended claims all such changes andmodifications that are within the scope of this invention.

What is claimed is:
 1. A process for making a fibrous structurecomprising a hydroxyl polymer structure, wherein the fibrous structurecomprises fused regions and exhibits a CETM Factor of less than 20, theprocess comprising the steps of: a. producing a hydroxyl polymerstructure in the form of a fiber by polymer processing a polymercomposition comprising from about 30% to about 90% by weight of one ormore hydroxyl polymers, from about 0.1% to about 10% by weight of acrosslinking agent, and from about 10% to about 70% by weight of water;b. forming a fibrous structure comprising the hydroxyl polymer fiber; c.subjecting the fibrous structure to a thermal bonding operation suchthat the fibrous structure comprising fused regions and exhibiting aCETM Factor of less than 20 is formed.
 2. The process according to claim1 wherein the polymer composition comprises at least two differentclasses of hydroxyl polymers.
 3. The process according to claim 2wherein one of the at least two different classes of hydroxyl polymerscomprises a thermoplasticizable hydroxyl polymer.
 4. The processaccording to claim 3 wherein the thermoplasticizable hydroxyl polymercomprises a polysaccharide hydroxyl polymer.
 5. The process according toclaim 4 wherein the polysaccharide hydroxyl polymer comprises a starchhydroxyl polymer.
 6. The process according to claim 2 wherein one of theat least two different class of hydroxyl polymers comprises aninherently thermoplastic hydroxyl polymer.
 7. The process according toclaim 6 wherein the inherently thermoplastic hydroxyl polymer comprisesa polyvinyl alcohol hydroxyl polymer.
 8. The process according to claim1 wherein the process further comprises a step of subjecting the fibrousstructure to a hyperbaric deflection process.
 9. The process accordingto claim 1 wherein the step of subjecting the fibrous structure to athermal bonding operation comprises imparting to the fibrous structure atemperature that is above the Tg of at least one of the hydroxylpolymers making up the hydroxyl polymer fiber.
 10. The process accordingto claim 9 wherein the temperature is at least about 70° C.